Defining a class of VLF objects

To define a class of VLF objects, issue the COFDEFIN macro. When you issue COFDEFIN, VLF uses information you specify on the macro and information from the active COFVLFxx member of SYS1.PARMLIB to prepare to process objects in that class. You must issue COFDEFIN for each class of objects that you want VLF to process.

To issue COFDEFIN specify:

The class name. This name must match a class described on a CLASS statement in COFVLFxx.
The length of the major names in the class. The default length (and only valid length) for a PDS class is 50.
The length of the minor names in the class. The default length (and only valid length) for a PDS class is 8.

Note that you do not specify eligible major names on COFDEFIN. VLF obtains the eligible major names for the class from the CLASS statement in COFVLFxx.

If you want to make sure that only authorized code can retrieve objects, specify AUTHRET=YES when you define the class.

The CLASS statement in COFVLFxx defines the amount of virtual storage available for a class. On the COFDEFIN macro, however, you indicate how you want VLF to manage virtual storage for the objects in the class. If you specify TRIM=ON, which is the default, VLF automatically removes the least recently used objects when it needs space. If you specify TRIM=OFF, VLF removes objects only when it is specifically notified. Allowing VLF to manage the storage (TRIM=ON) ensures that, if space is limited, the most recently used objects tend to remain in virtual storage.